Current Knowledge on Nail Involvement in Autoimmune Bullous Disorders

Background: There are few studies, mainly case reports, on the involvement of the nail unit in autoimmune bullous disorders. Summary: Nail involvement in autoimmune bullous disorders is a significant clinical phenomenon, marked by a range of manifestations, most often not presenting with blisters like on the skin but rather with alterations of the nail unit such as paronychia, onychomadesis, or onycholysis. This involvement is particularly notable due to the unique immunological features of the nail unit, including the expression of various antigens and the presence of Langerhans cells. Conditions like pemphigus vulgaris, bullous pemphigoid, epidermolysis bullosa acquisita, linear IgA disease, and bullous systemic lupus erythematosus can lead to nail abnormalities. The prevalence of nail manifestations varies according to the disorder, and diagnosis often relies on histopathological and immunofluorescence testing. Nail involvement correlates with disease severity and duration, sometimes serving as a herald sign. Further research is needed to guide therapeutic approaches for nail involvement in autoimmune bullous diseases. Key Messages: Nail involvement in autoimmune bullous nail disorders may be confusing as there are almost never bullae. One should keep the diagnosis in mind when facing an atypical paronychia.